ESP32-LyraTD-SYNA is a high-end voice and audio development board based on the ESP32-WROVER-E/B module. Its core highlight is the integration of the Synaptics Cx20921 DSP chip and a dual-microphone array, providing professional-grade Acoustic Echo Cancellation (AEC), Noise Suppression (NS), and far-field voice pickup capabilities. It is specifically designed for smart speakers, voice assistants, and voice-controlled devices.
1. Core Positioning and Architecture
| Item | Details |
|---|---|
| Product Type | High-end voice audio development board (not a standalone module, but a fully integrated development platform) |
| Main Controller | ESP32-WROVER-E/B module (dual-core Xtensa LX6 processor, up to 240 MHz) |
| Audio Processing | Synaptics Cx20921 DSP chip (professional voice processing with AEC/NS support) |
| Memory Configuration | 16 MB SPI Flash + 8 MB PSRAM (some versions with 4 MB Flash) |
| Wireless Capability | 2.4 GHz Wi-Fi (802.11 b/g/n) + Bluetooth 4.2 (BLE) dual-mode connectivity |
| Power Supply | USB Type-C 5 V input, supports external power supply (5–12 V) |
Core Advantage: A dual-core architecture of “ESP32 main MCU + professional DSP”, where the ESP32 handles networking and application logic, while the Synaptics DSP focuses on voice signal processing, delivering low-latency and high-quality voice interaction.
2. Hardware Features in Detail
1. Professional Voice Processing System
- Dual-Microphone Array: High-sensitivity MEMS microphones supporting far-field voice pickup (3–5 meters) with DSP-based beamforming
- Synaptics Cx20921 DSP: Built-in AEC, Noise Suppression (NS), and Automatic Gain Control (AGC) algorithms
- Audio Codec: 2-channel DAC (16/24-bit) and 2-channel ADC (16-bit), supporting high-fidelity audio output
- Audio Interfaces: 3.5 mm headphone jack, speaker output (supports 8Ω / 3W speaker), and I2S digital audio interface
2. Expansion and Control Interfaces
| Interface Type | Quantity | Function Description |
|---|---|---|
| Function Buttons | 3 | 2 user-defined buttons (Play/Pause, Voice Wake), 1 system reset button |
| LED Indicators | 3 | Power LED, Wi-Fi status LED, user-defined LED |
| Microphone Interfaces | 2 | On-board MEMS microphones, supports external microphone array expansion |
| USB Type-C | 1 | Power, programming, and debugging with USB Serial/JTAG |
| Expansion Interface | 1 set | Includes I2C, SPI, UART, GPIO, compatible with some Arduino expansion boards |
| FPC Connector | 1 | Supports external display or camera modules |
| Storage Expansion | 1 | Micro SD card slot, supports up to 32 GB for local audio playback |
3. Other Hardware Features
- On-board PCB antenna, optional external IPEX antenna for improved Wi-Fi/Bluetooth signal
- Power management circuit with stable 3.3 V/5 V outputs and overcurrent/overvoltage protection
- 5V/3.3V Logic Compatibility: All GPIO pins are 5V tolerant, reducing hardware design risk
- Industrial-grade design with operating temperature range -40°C to +85°C
3. Software Support and Development Environment
1. Official Development Frameworks
- ESP-VA-SDK (Voice Assistant SDK): Designed for voice interaction, integrating AEC/NS, wake-word detection, and speech recognition
- ESP-ADF (Audio Development Framework): Complete audio processing components (codec, effects, playback control)
- ESP-IDF (IoT Development Framework): Core framework supporting Wi-Fi, Bluetooth, and peripheral drivers
- ESP-Skainet: Offline speech recognition for local voice control without internet connectivity
2. Voice Platform Support
- Compatible with mainstream voice assistant platforms: Amazon AVS (Alexa), Google Dialogflow, Google GVA (Google Voice Assistant)
- Supports custom wake words for personalized voice interaction
- Supports multiple audio codecs: WAV, MP3, AAC, FLAC, OPUS, OGG, with no quality loss
3. Third-Party Development Support
- Supports Arduino and MicroPython to lower development barriers
- Rich open-source libraries for quick implementation of wake-word detection, audio playback, and Wi-Fi connectivity
- Supports OTA firmware updates via Wi-Fi for easy maintenance and feature iteration
4. Typical Application Scenarios
1. Smart Voice Assistant Devices
- Far-field smart speakers: 3–5 m voice control for music playback, information queries, and smart home control
- Voice control hub: With AEC, voice commands can be recognized accurately even during music playback
- Industrial voice terminals: Voice control in noisy environments for device operation and data queries
2. Smart Home Voice Control
- Voice-controlled switches: Use ESP32 GPIO expansion to control lights, curtains, air conditioners, etc.
- Voice alarm systems: Voice alerts when abnormal conditions are detected
- Smart appliance voice panels: Replace traditional buttons with natural voice-based HMI
3. Automotive Voice Systems
- In-vehicle voice assistant: Control navigation, music, and calls while driving
- Bluetooth hands-free system: AEC reduces cabin noise to improve call quality
- Vehicle information queries: Voice access to vehicle status, weather, and traffic data
4. Other Professional Audio Applications
- Conference microphone systems: Dual-mic array + DSP improves speech clarity
- Voice recording and transcription devices: High-quality recording and real-time speech-to-text
- Smart toys with voice interaction capabilities
5. Key Technical Advantages
| Advantage | Application Value |
|---|---|
| ESP32 + Synaptics DSP Dual-Core Architecture | Clear task separation: ESP32 for networking/app logic, DSP for voice processing, reducing latency |
| Professional AEC | Enables “talk-while-playing” capability with accurate voice recognition during playback |
| Far-Field Voice Pickup (3–5 m) | Hands-free control without close proximity |
| Broad Voice Platform Compatibility | Faster integration into mainstream voice ecosystems |
| Large Memory (16 MB Flash + 8 MB PSRAM) | Supports offline voice models and local audio storage |
| Industrial-Grade Reliability | Suitable for commercial and harsh environment deployments |
6. Quick Specification Overview
| Parameter | Specification |
|---|---|
| Processor | Dual-core Xtensa LX6, up to 240 MHz |
| Memory | 520 KB SRAM, 16 MB Flash, 8 MB PSRAM |
| Voice Processing | Synaptics Cx20921 DSP with AEC/NS/AGC |
| Microphones | 2 on-board MEMS microphones, far-field pickup (3–5 m) |
| Audio Output | 3.5 mm headphone jack, supports 8Ω / 3W speaker |
| Wireless Range | Wi-Fi: 100 m (open area), BLE: 50 m (open area) |
| Operating Temperature | -40°C to +85°C (industrial grade) |
| Dimensions | ~100 mm × 60 mm (compact design) |
| Weight | ~45 g |
Summary
ESP32-LyraTD-SYNA is a classic high-end voice audio development board. Its “ESP32 + professional DSP” architecture provides a complete solution for voice-interactive device development. Although discontinued, its design philosophy and technical approach remain highly valuable for future products—especially for smart speakers, voice assistants, and other applications requiring professional-grade AEC and far-field voice capabilities.
